Method and apparatus for controlling generation of electrostatic friction effects for a plurality of electrodes

ABSTRACT

An interface device configured to provide an electrostatic friction (ESF) effect is disclosed. The interface device comprises a plurality of electrodes disposed at a surface of the interface device. It further comprises a signal generating circuit configured to generate a first drive signal at an output of the signal generating circuit, and comprises a plurality of frequency filter units or delay elements electrically connected to the signal generating circuit and to the plurality of electrodes. The interface device further comprises a control unit configured to use the plurality of frequency filter units or delay elements: (i) to cause only a subset of one or more electrodes of the plurality of electrodes to output one or more respective ESF effects with the first drive signal, or (ii) to cause at least two electrodes to output respective ESF effects with the first drive signal in different respective manners.

FIELD OF THE INVENTION

The present invention is directed to a method and apparatus forcontrolling generation of electrostatic friction effects for a pluralityof electrodes, and has application in wearables, user interfaces,gaming, automotive, virtual reality or augmented reality, and consumerelectronics.

BACKGROUND

As computer-based systems become more prevalent, the quality of theinterfaces through which humans interact with these systems is becomingincreasingly important. Haptic feedback, or more generally hapticeffects, can improve the quality of the interfaces by providing cues tousers, providing alerts of specific events, or providing realisticfeedback to create greater sensory immersion within a virtualenvironment.

Examples of haptic effects include kinesthetic haptic effects (such asactive and resistive force feedback), vibrotactile haptic effects, andelectrostatic friction haptic effects. In electrostatic friction hapticeffects, a current may be provided to an electrode. The electrode maythen exert an attractive force on the skin of a user, who may perceivethis force as electrostatic friction.

SUMMARY

One aspect of the embodiments herein relates to an interface deviceconfigured to provide an electrostatic friction (ESF) effect. Theinterface device comprises a plurality of electrodes, a signalgenerating circuit, a plurality of frequency filter units or delayelements, and a control unit. The plurality of electrodes are disposedat a surface of the interface device. The signal generating circuit isconfigured to generate a first drive signal at an output of the signalgenerating circuit. The plurality of frequency filter units or delayelements are electrically connected to the signal generating circuit andto the plurality of electrodes, such that each electrode of theplurality of electrodes is electrically connected to an output of arespective frequency filter unit or delay element. An input of therespective frequency filter unit or delay element is electricallyconnected to the output of the signal generating circuit. The controlunit is configured to use the plurality of frequency filter units ordelay elements: (i) to cause only a subset of one or more electrodes ofthe plurality of electrodes to output one or more respective ESF effectswith the first drive signal, or (ii) to cause at least two electrodes ofthe plurality of electrodes to output respective ESF effects with thefirst drive signal in different respective manners.

In an embodiment, the interface device comprises the plurality offrequency filter units. Each of the plurality of frequency filter unitshas a respective pass-through frequency band or a respective set ofpass-through frequency bands, and is configured to block any frequencycomponent of the first drive signal which is outside the respectivepass-through frequency band or respective set of pass-through frequencybands. The respective pass-through frequency bands or respective sets ofpass-through frequency bands of the plurality of frequency filter unitsdo not overlap in frequency, or only partially overlap in frequency.

In an embodiment, the control unit is configured to cause the signalgenerating circuit to generate the first drive signal with only afrequency component that is (i) within the respective pass-throughfrequency band or respective set of pass-through frequency bands of arespective frequency filter unit of a first electrode and (ii) outsidethe respective pass-through frequency bands or respective sets ofpass-through frequency bands of the remainder of the plurality offrequency filter units of the remainder of the plurality of electrodesof the interface device, such that the plurality of frequency filterunits causes only the first electrode of the plurality of electrodes tooutput an ESF effect with the first drive signal.

In an embodiment, each of the plurality of frequency filter units hasonly a single respective pass-through frequency band, and the respectivepass-through frequency bands of the plurality of frequency filter unitsdo not overlap in frequency, or each of the plurality of frequencyfilter units has a respective set of pass-through frequency bands, andthe respective sets of pass-through frequency bands of the plurality offrequency filter units have partial overlap in frequency.

In an embodiment, the plurality of frequency filter units comprise afirst frequency filter unit configured to pass the first drive signal toa first electrode of the plurality of electrodes with a firstattenuation level, and comprises a second frequency filter unitconfigured to pass the first drive signal to a second electrode of theplurality of electrodes with a second attenuation level different thanthe first attenuation level. The interface device is configured to causethe first electrode and the second electrode to output respective ESFeffect with the first drive signal with different respective intensitylevels.

In an embodiment, the plurality of frequency filter units comprise afirst frequency filter unit configured to pass the first drive signal toa first electrode of the plurality of electrodes with a first phaseshift that creates a first period of delay, and comprises a secondfrequency filter unit configured to pass the first drive signal to asecond electrode of the plurality of electrodes with a second phaseshift that creates a second period of delay different than the firstperiod of delay, and wherein the interface device is configured to causethe first electrode and the second electrode to output respective ESFeffects with the first drive signal at different respective times.

In an embodiment, the control unit is configured to determine a spatialrelationship between the interface device and a determined location, orto determine a temporal relationship between a current time and adetermined event, and is configured to select the subset of one or moreelectrodes to convey the spatial relationship or the temporalrelationship.

In an embodiment, the interface device comprises the plurality offrequency filter units. The first drive signal is one of a plurality ofdrive signals the signal generating circuit is configured to generate indifferent respective time periods or in response to different signalgenerating commands. The control unit is configured to cause theplurality of frequency filter units to pass the plurality of drivesignals to different respective electrodes of the plurality ofelectrodes.

In an embodiment, the plurality of electrodes are arranged as an array.The control unit is configured to use the plurality of frequency filterunits to cause the array of electrodes to sequentially output respectiveESF effects with the respective drive signals to create an impression offlow along the array of electrodes.

In an embodiment, the interface device comprises the plurality of delayelements, wherein the plurality of delay elements are configured tocontrol a timing by which each electrode of the plurality of electrodeswill output an ESF effect by introducing different respective periods ofdelay of the first drive signal from an input of the respective delayelement to an output of the respective delay element.

In an embodiment, the plurality of electrodes is arranged in an array inwhich the plurality of electrodes has uniform spacing between adjacentelectrodes.

In an embodiment, the array is a two-dimensional array.

In an embodiment, the interface device is a wearable device.

In an embodiment, the signal generating circuit comprises an amplifiercircuit configured to amplify a first signal to the first drive signal,wherein the amplifier circuit is the only amplifier circuit in theinterface device for amplifying the first signal to the first drivesignal.

In an embodiment, the control unit is configured to select the subset ofone or more electrodes from among a set of electrodes of the pluralityof electrodes that are receiving user contact, such that some electrodesreceiving user contact are not selected to generate a respective staticESF effect with the first drive signal.

One aspect of the embodiments herein relates to an interface deviceconfigured to provide an electrostatic friction (ESF) effect. Theinterface device comprises a signal generating circuit, a plurality ofdelay elements, and a plurality of electrodes. The signal generatingcircuit is configured to generate a first drive signal at an output ofthe signal generating circuit. The plurality of delay elements areconfigured to introduce respective periods of delay to the first drivesignal from an input of the respective delay element to an output of therespective delay element. The plurality of electrodes correspond to theplurality of delay elements, wherein each of the plurality of electrodesis connected to an output of a respective delay element and isconfigured to generate a respective ESF effect with the first drivesignal. The plurality of delay elements and their respective electrodesform a plurality of respective pairs that each includes a respectivedelay element and a respective electrode. The plurality of pairs ofdelay elements and their respective electrodes are electricallyconnected in series such that an input of a delay element of a firstpair in the series is connected to an output of the signal generatingcircuit, and an input of a delay element of all other pairs in theseries is electrically connected to an electrode of a previous pair inthe series.

In an embodiment, the respective periods of delay introduced by theplurality of delay elements are the same.

In an embodiment, the respective periods of delay introduced by theplurality of delay elements are all different. Features, objects, andadvantages of embodiments hereof will become apparent to those skilledin the art by reading the following detailed description wherereferences will be made to the appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will beapparent from the following description of embodiments hereof asillustrated in the accompanying drawings. The accompanying drawings,which are incorporated herein and form a part of the specification,further serve to explain the principles of the invention and to enable aperson skilled in the pertinent art to make and use the invention. Thedrawings are not to scale.

FIG. 1A is a depiction of a wearable device having a plurality ofelectrodes disposed at an outer surface thereof to generateelectrostatic friction effects, according to an embodiment herein.

FIG. 1B is a depiction of a wearable device having a plurality ofelectrodes disposed at an outer surface thereof to generateelectrostatic friction effects, according to an embodiment herein.

FIG. 2 is a depiction of a mobile device having a plurality ofelectrodes disposed at an outer surface thereof to generateelectrostatic friction effects, according to an embodiment herein.

FIG. 3 is a depiction of a laptop having a plurality of electrodesdisposed at an outer surface thereof to generate electrostatic frictioneffects, according to an embodiment herein.

FIGS. 4A and 4B are schematic representations of a plurality of gatingelements disposed between a driving circuit and respective electrodes,according to an embodiment herein.

FIGS. 5A and 5B are schematic representations of a plurality of gatingelements that are frequency filter units, according to an embodimentherein.

FIG. 6A is a schematic representation of a plurality of delay elementsconnected to a signal generating circuit in a parallel fashion,according to an embodiment herein.

FIG. 6B is a schematic representation of a plurality of delay elementsconnected to each other in a series fashion, according to an embodimentherein.

FIG. 7 is a schematic representation of a plurality of gating elementsthat are relay switches, according to an embodiment herein.

FIGS. 8A and 8B are schematic representations of an interface devicehaving a plurality of gating elements connected between respectiveelectrodes and a ground potential, according to an embodiment herein.

FIG. 9 is a schematic representation of a plurality of shieldingelements of a shielding layer that are configured to shield respectiveelectrodes from a surface of an interface device, according to anembodiment herein.

FIG. 10 is a schematic representation of a plurality of shieldingelements that are configured to shield respective electrodes from asurface of an interface device, according to an embodiment herein.

FIGS. 11A and 11B illustrate a plurality of electrodes being used toconvey a spatial or temporal relationship, according to an embodimentherein.

FIG. 12 illustrates an example layout of a plurality of electrodes forgenerating respective ESF effects, according to an embodiment herein.

FIG. 13 illustrates an example layout of a plurality of electrodes forgenerating respective ESF effects, according to an embodiment herein.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Furthermore, there is no intention to be bound by anyexpressed or implied theory presented in the preceding technical field,background, brief summary or the following detailed description.

Embodiments hereof relate to implementing a haptic enabled interfacedevice (e.g., a handheld or otherwise graspable device such as a mobiledevice or game console controller, a wearable device, a laptop) whichincludes a plurality of electrodes for producing (e.g., generating)electrostatic friction (ESF) effects, and is configured to control whichsubset of one or more electrodes will generate one or more respectiveESF effects with a drive signal, and/or is configured to vary howdifferent electrodes generate respective ESF effects with the drivesignal. For example, the haptic enabled interface device may includefrequency filter units or relay switches which are configured to blockthe drive signal from reaching certain electrodes, or include shieldingelements which are configured to electrically shield those electrodesfrom a surface of the device, so that those electrodes do not generateany ESF effect with the drive signal at the surface. In another example,the haptic enabled interface device may be configured to pass a drivesignal to multiple electrodes, but may attenuate or delay the drivesignal by different amounts/periods for different electrodes, so thatthe different electrodes generate respective ESF effects with the drivesignal in different manners. The frequency filter units, delay elements,and relay switches may be different types of gating elements.

In an embodiment, the haptic enabled interface device may be configuredto control which electrodes output respective ESF effects with a drivesignal and/or how those electrodes output the ESF effects with the drivesignal in order to convey a spatial relationship, a temporalrelationship, a spatio-temporal relationship (e.g., a combination of aspatial relationship and a temporal relationship), and/or otherinformation to a user. In an embodiment, the plurality of electrodes maysequentially output respective ESF effects to create an impression offlow along the electrodes. For instance, if the electrodes are arrangedin a one-dimensional array (e.g., a line) or a two-dimensional array,the sequential output of the respective ESF effects along the array maycreate an impression of flow along the array. This impression of flowmay be used to provide navigation instructions for a user, indicateprogress of an operation, a passage of time, or for any other purpose.

In an embodiment, the plurality of electrodes may be used to produce(e.g., generate) static ESF effects. As discussed in more detail below,dynamic ESF effects may require a user to move a part of his or her body(e.g., finger tip) across an electrode, while static ESF effects allowthe user's body (e.g., finger tip) to remain stationary. In some cases,static ESF effects may use a much higher voltage (e.g., 1.5 kV) thanthat used with dynamic ESF effects (e.g., 10 V). Thus, in someinstances, a signal generating circuit of the haptic enabled device mayuse one or more amplifier circuits that include high-voltage electronicsto generate a high-voltage drive signal for static ESF. For example, thedrive signal may be an amplified signal with an amplitude (e.g., >1 kV)suitable for static ESF effects. In an embodiment, the haptic enabledinterface device may include multiple amplifier circuits, with oneamplifier circuit assigned to each electrode, so that the output of ESFeffects can be separately controlled at each individual electrode. Inanother embodiment, the haptic enabled interface device may include onlyone amplifier circuit for generating any drive signal. The soleamplifier circuit may be included in the signal generating circuit. Inthis embodiment, the amplifier circuit outputs a drive signal that canbe shared among the plurality of electrodes, which may producerespective ESF effects using the same drive signal. For instance, aplurality of individually controllable gating elements (e.g., switches,frequency filter units, or delay elements) may be placed between thesingle amplifier circuit and the respective electrodes to control ESFeffects at those electrodes, or a plurality of shielding elements may beplaced between the respective electrodes and a ground potential tocontrol ESF effects at those electrodes. The gating elements orshielding elements may, e.g., cause only a subset of one or moreelectrodes of a plurality of electrodes to output respective one or moreESF effects with a first drive signal, or may cause at least twoelectrodes of the plurality of electrodes to output respective ESFeffects with the first drive signal, but to do so in different manners.In another instance, a plurality of delay elements may be arranged in aseries configuration to form a chain of delay elements, with each delayelement gating a respective electrode. This series arrangement may causea drive signal to sequentially propagate through the chain of delayelements and their respective electrodes to create the impression offlow, for instance.

FIGS. 1A and 1B are depictions of a wearable interface device (e.g., anactivity tracker wristband or smart watch) configured to provide anelectrostatic friction (ESF) effect to a user. FIG. 1A depicts awearable interface device 100 that has a band 101 with a first surface101 a and a second, opposite surface 101 b. The first surface 101 a may,e.g., be a top outer surface intended to be visible and/or accessiblewhen worn, and the second surface 101 b may be, e.g., a bottom outersurface intended to contact a user's wrist when worn. The second surface101 b may be referred to as a contact surface. In FIG. 1A, the secondsurface 101 b of the band 101 may have a plurality of electrodes 103a-103 h disposed at the surface 101 b. In an embodiment, the firstsurface 101 a may have a display device (e.g., touch screen) and/or aphysical user input component (e.g., a button) mounted thereon, or mayalternatively have none of those devices (e.g., as a simpler activitytracker). In an embodiment, the wearable interface device 100 mayinclude another haptic device. For instance, the wearable interfacedevice 100 may include a piezoelectric actuator embedded within the band101 to produce a vibrotactile haptic effect for the whole band 101, or alayer of shape memory alloy disposed on the first surface 101 a toproduce a deformation haptic effect at the first surface 101 a.

The electrodes used to produce ESF effects (which may be referred to asESF electrodes) may have a variety of sizes and shapes, such as squares,dots, and strips. For instance, FIG. 1B depicts another wearableinterface device 200 that has a plurality of electrodes 203 a-203 e on aband 201, which are different in size and shape than the electrodes 103a-103 h in FIG. 1A. More specifically, the electrodes 203 a-203 e mayeach have the form of a long strip having a length substantially equalto a length of the band 201. In some cases, an electrode shaped as along strip may be more advantageous compared to some other shapesbecause an ESF effect for some users may be more optimal when their skindoes not completely cover an electrode. An electrode having the longstrip shape may be less likely to be completely covered by the skin of auser. The electrodes in the embodiments herein may also be arranged in avariety of orientations. For instance, the electrodes 103 a-103 h may belined up along a length of the band 101, while the electrodes 203 a-203e may be rotated 90 degrees from as shown in FIG. 1B to be lined upalong a width of the band 201. In an embodiment, these two orientationsmay be combined, with some electrodes lined up along a length of a band(FIG. 1B), while some electrodes are lined up along a width of the band.

As discussed above, the electrodes 103 a-103 h or the electrodes 203a-203 e may be used to create spatial and/or temporal feedback, such asto create an impression of flow of ESF effects along the electrodes, orto convey a spatial direction for a user to follow. With respect to FIG.1A, sequential ESF effects, or the flow of ESF effects, along theelectrodes 103 a-103 h may be used to direct a user in a leftwarddirection of a rightward direction. With respect to FIG. 1B, sequentialESF effects, or the flow of ESF effects, along the electrodes 203 a-203e may be used to direct a user in a forward or a backward direction. Thearrangement of electrodes in FIG. 1A may be combined with thearrangement of electrodes in FIG. 1B to allow a haptic enabled interfacedevice to direct a user in a forward, backward, leftward, or rightwarddirection.

In another example, the electrodes 103 a-103 h or the electrodes 203a-203 e may be used to indicate a spatial orientation of thecorresponding haptic enabled interface device (and of a user wearing thedevice) relative to a location of interest. For example, electrode 103 dor 103 e may be designated as a center electrode that represents acurrent location of the device, while electrode 103 b may be determinedto fall on a left side of the center electrode when the strap 101 isworn, and electrode 103 g may be determined to fall on a right side ofthe center electrode when strap 101 is worn. When a desired destinationor object is to the left of the device's current location, a drivesignal may be directed to the electrode 103 b to output an ESF effect.When the desired destination or object is to the right of the device'scurrent location, the drive signal may be directed to the electrode 103g to output an ESF effect.

In another example, the electrodes 103 a-103 h may be used to convey atemporal relationship between a current time and an event of interest.For example, each of the electrodes 103 a-103 h may correspond todifferent amounts of time (e.g., 15 minutes, 30 minutes, etc.) before ameeting, and may be selectively activated to indicate a current durationof time before a meeting. In yet another example, the electrodes 103a-103 h may be used to indicate progress of an operation, such as a datatransfer operation. For instance, electrodes 103 a-103 h may correspondto different percentages (e.g., 0%, 10%, 20%, etc.), and may beselectively activated to indicate what percentage of the data transferoperation is currently complete.

FIGS. 2 and 3 depict examples of other interface devices having ESFelectrodes for producing (e.g., generating) an ESF effect. FIG. 2 showsan example of a mobile interface device 300 (e.g., smartphone or tabletcomputer) having a plurality of electrodes 303 a-303 g disposed at acontact surface 301 (e.g., a back surface) thereof. The contact surfaceof the device 300 may be a surface that is expected to receive usercontact from a hand when the device 300 is held by that hand. Theelectrodes 303 a-303 g may each be shaped as a circle (e.g., a dot), andmay be arranged in a two-dimensional array (e.g., four rows by twocolumns). The electrodes may be placed, e.g., at locations on thecontact surface 301 where a user's finger is most likely to touch whenholding the mobile interface device 300. FIG. 3 depicts an example of alaptop 400 having a plurality of electrodes 403 a-403 f on a contactsurface (e.g., palm rest, touch pad 409, hand print scanner) thereof.The contact surface of the device 400 may be a surface that is expectedto receive user contact during typing or other use of the device 400.The electrodes 403 a-403 f may be arranged as a first one-dimensionalarray 413 and a second one-dimensional array 423. The firstone-dimensional array 413 is located on one side of a touch pad 409, andthe second one-dimensional array 423 is located on an opposite side ofthe touch pad 409. These locations may correspond to areas where auser's wrist is likely to come to rest and contact the laptop 400,allowing the ESF effect to be generated at the user's wrist. In anembodiment, the ESF electrodes described herein may be disposed at asurface of a display screen of device 300, device 400, or of any otherdevice having a display screen. In an embodiment where a plurality ofelectrodes (e.g., 103 a-103 h) are arranged as an array, the pluralityof electrodes may have uniform spacing between adjacent electrodes.

The electrodes 103 a-103 h, 203 a-203 e, 303 a-303 h, 403 a-403 f may beconfigured to generate an ESF effect, and may be referred to as ESFelectrodes. In an embodiment, each electrode may be a conductive (e.g.,metal) pad. In an embodiment, the plurality of electrodes 103 a-103 h,203 a-203 e, 303 a-303 h, 403 a-403 f may be exposed electrodes and/orinsulated electrodes. Some haptic enabled interface devices may includeonly exposed ESF electrodes, include only insulated ESF electrodes, orinclude a mixture of exposed ESF electrodes and insulated ESFelectrodes. An exposed electrode may be disposed at a respective portionof a surface of an interface device (e.g., surface 101 b), and morespecifically may form the respective portion of the surface. The exposedelectrode may, e.g., be configured to be directly electrically coupledto a user upon the user making contact with the exposed electrode (ordisposed over the exposed electrode with only a very small air gaptherebetween) at the respective portion of the surface. The contact mayrefer to contact with, e.g., the user's skin. More generally speaking,the contact may refer to contact in which a drive signal can create anelectrostatic friction effect on the user's body. In one example, anexposed electrode may be a conductive pad adhered on top of a body ofthe interface device (e.g., on top of a body of band 101). In oneexample, the exposed electrode may be a conductive pad exposed throughan opening in a body, a housing or other structural element of theinterface device (e.g., through an opening in a casing of a mobilephone).

In an embodiment, an insulated electrode may be disposed at a respectiveportion of an outer surface (e.g., surface 101 b) of an interfacedevice, and more specifically may be disposed behind the respectiveportion of the outer surface. The insulated electrode may, e.g., beseparated from the surface by a thin insulating layer, such as a layerof dielectric material. The insulated layer may be configured to becapacitively electrically coupled to a user upon the user making contactwith the insulated electrode's respective portion of the surface. In oneexample, an insulated electrode may be embedded within a plastic outercover of a mobile phone or game console controller, or embedded within aband of a smart watch, such that there is an electrically insulatingmaterial (e.g., a dielectric material) between the electrode and theouter surface of the mobile phone, game console controller, or smartwatch. In another example, the insulated electrodes may be a conductivematerial placed on a body of the smart phone, smart watch, or gameconsole controller, and may have then been covered with an insulatingmaterial (e.g., a layer of Kapton® tape).

In an embodiment, the multiple electrodes may be used, e.g., to generatea static ESF effect or a dynamic ESF effect. Dynamic ESF effects mayinvolve exerting electrostatic forces on a finger or other part of theuser's body while the finger or other part of the user's body is movingon a surface of the interface device. The electrostatic forces may becreated by applying a time-varying signal to an electrode. Theelectrostatic forces may attract the finger, and may be perceived asfriction during the movement of the finger. Static ESF effects may begenerated while the user's finger or other body part remains stationaryrelative to and contacting a surface of the interface device. Static ESFeffects may also involve applying a time-varying signal to an electrodeto create electrostatic forces. In some cases, static ESF may involve ahigher voltage level for the time-varying signal compared to that fordynamic ESF.

In an embodiment, the handheld interface device 100 includes electrodeswhich are signal electrodes or switchable to being signal electrodes,and includes electrodes which are ground electrodes or switchable tobeing ground electrodes. For example, FIG. 4A shows an embodiment inwhich electrodes 103 a and 103 h are both ground electrodes, andelectrodes 103 b-103 g are signal electrodes or switchable by gatingelements 105 b-105 g to being signal electrodes. In an embodiment, asignal electrode may be an electrode that receives a drive signal from asignal generating circuit, and may be configured to produce an ESFeffect with the drive signal. In an embodiment, a ground electrode maybe an electrode electrically connected to a ground potential (e.g., aground potential as being equal to a potential of a negative terminal ofa battery or other power source of the interface device 100). Becauseelectrodes 103 a and 103 h have a permanent electrical connection toground, they may be referred to as dedicated ground electrodes in FIG.4A. Because electrodes 103 a and 103 h are dedicated ground electrodes,they have no corresponding gating elements (i.e., no gating element 105)in FIG. 4A. Generally speaking, a gating element for an electrode may bean element (e.g., circuit) which controls whether a signal can reach theelectrode, or a manner in which the signal reaches the electrode (e.g.,a level of attenuation or amplification, or a period of delay). In someexamples in which static ESF effects are generated, only an insulatedelectrode(s) is used as a signal electrode, while an insulated electrodeor an exposed electrode (if any) may be used as a ground electrode. Insome cases, an insulated electrode is switchable between being a signalelectrode and a ground electrode (e.g., interchangeably used as a signalelectrode at one point in time (a first instance) or as a groundelectrode at another point in time (a second instance).

Returning to FIG. 4A, the figure is a schematic representation of thewearable interface device 100, which includes a signal generatingcircuit 104 that includes a signal processor 106 and an amplifier 108.The signal processor 106 may be configured to generate, e.g., asinusoidal or other time-varying signal for producing an ESF effect. Thesignal generated by the signal processor 106 may be an analog or digitalsignal. In an embodiment, the interface device 100 may include a controlunit 110 (e.g., a microprocessor or FPGA circuit) that is configured tocontrol the signal generated by the signal processor 106. The amplifier108 may be configured to amplify the signal from the signal processor106 to generate a drive signal at an output of the signal generatingcircuit 104. For instance, the signal generated by the signal processor106 may be a rectangular pulse having an amplitude that is in a range of5 V to 10 V, and the amplifier 108 may amplify this signal to generate adrive signal that is a rectangular pulse with an amplitude of about 1 kVfor producing a static ESF effect. In an embodiment, the amplifier 108may be the only amplifier in the interface device 100 for amplifying anysignal from the signal processor 106.

In an embodiment, the signal generating circuit 104 may output a firstdrive signal and a second drive signal which correspond to separate timeperiods, or separate signal generating commands. For example, a voltagewaveform that is output by the signal generating circuit 104 in a firsttime period (e.g., first 1-second window) may be considered a firstdrive signal, while a voltage waveform that is output by the signalgenerating circuit 104 in a second time period (e.g., a subsequent1-second window) may be considered a second drive signal. In anotherexample, a voltage waveform that is output by the signal generatingcircuit 104 in response to a first signal generating command from asoftware application (e.g., device driver) or application programminginterface (API) controlling control unit 110 may be considered a firstdrive signal, while a voltage waveform that is output by the signalgenerating circuit 104 in response to a second signal generating commandmay be considered a second drive signal. In an embodiment, a firstelectrode that receives a drive signal may be considered to begenerating a first ESF effect, while a second electrode that receivesthe same drive signal may be considered to be producing a second ESFeffect. The two electrodes may receive the same version of the drivesignal (e.g., same intensity, same phase, and same frequency components)or different versions (e.g., different intensities, different phases, ordifferent frequency components) of the same drive signal.

In an embodiment, a plurality of gating elements 105 b-105 g may bedisposed between respective electrodes 103 b-103 g and an output of thesignal generating circuit 104, to control which of the electrodes 103b-103 g will be signal electrodes. Examples of a gating element includea frequency filter, a delay element, and a switch (e.g., a high-voltagerelay switch or high-voltage transistor). The plurality of gatingelements 105 b-105 g may be configured to control which electrode(s) ofthe electrodes 103 b-103 g will receive a drive signal from the outputof the signal generating circuit 104, and/or control a manner in whichthe drive signal reaches an electrode, such as an attenuation level orperiod of delay (e.g., from a phase shift) of the drive signal inreaching the electrode. In an embodiment, the relay switches orhigh-voltage transistors may form a high-voltage multiplexer thatelectrically connect a drive signal to exactly one electrode ofelectrodes 103 b-103 g, which may be selected under software control.

In FIG. 4A, the properties of the gating elements 105 b-105 g may befixed. For instance, if the gating elements are frequency filters, eachof the frequency filters may have a fixed pass-through frequencyband(s). If the gating elements are delay elements, each of the delayelements may have a fixed time delay by which it delays a drive signalfrom the signal generating circuit 104. FIG. 4B depicts gating elementsthat are re-configurable. More specifically, FIG. 4B also depicts aninterface device 100 having a plurality of gating elements 105 b′-105 g′disposed between an output of the signal generating circuit 104 andrespective electrodes 103 b-103 g. In FIG. 4B, the properties of thegating elements 105 b′-105 g′ may be reconfigured by the control unit110 through respective CTRL input lines. For instance, if in anembodiment the gating elements are frequency filters, the control unitmay be configured to communicate a command to a CTRL input line of atleast one of the frequency filters to re-configure a pass-throughfrequency band(s) of the frequency filter. If in an embodiment thegating elements are delay elements, the control unit 110 may beconfigured to communicate a command to a CTRL input line of at least oneof the delay elements to re-configure a period of delay that the delayelement will introduce to a signal. If in an embodiment the gatingelements are a plurality of switches (e.g., relay switches), the controlunit 110 may be configured to control (e.g., open or close) each of theswitches via respective CTRL input lines.

In an embodiment, the control unit 110 is configured to select a subsetof one or more electrodes from the set of electrodes 103 a-103 h, orfrom the set of electrodes 103 b-103 g that are switchable to beingsignal electrodes, for outputting an ESF effect with a drive signal. Thecontrol unit may be configured to select a subset of one or moreelectrodes (e.g., 103 b) from among a set of electrodes (e.g., 103 b,103 c, 103 d) that are receiving user contact, such that the electrodesreceiving user contact are not selected to produce a respective staticESF effect with a drive signal.

FIG. 5A is a schematic representation of an embodiment having gatingelements that are a plurality of frequency filter units (e.g., analog ordigital frequency filter units) 1105 b, 1105 c, 1105 d, respectively. Inan embodiment, each of the frequency filter units 1105 b, 1105 c, 1105 dmay be configured to have a different respective pass-through frequencyband. As shown in FIG. 5A, frequency filter unit 1105 b may have only asingle pass-through frequency band that is centered around 50 Hz.Frequency filter unit 1105 c may have only a single pass-throughfrequency band that is centered around 100 Hz. Frequency filter unit1105 d may have only a single pass-through frequency band that iscentered around 200 Hz. Each of the frequency filter units 1105 b, 1105c, and 1105 d may be configured to block any frequency component of adrive signal which is outside of its respective pass-through frequencyband. For instance, a drive signal which is a weighted sum of a 50 Hzsinusoidal signal and a 100 Hz sinusoidal signal will be blocked byfrequency filter unit 1105 d, because the frequency filter unit 1105 dhas only the single pass-through band centered around 200 Hz.

In an embodiment, a frequency filter unit may be configured to attenuatea frequency component of a signal that falls within a pass-through bandof the frequency filter unit. For a drive signal that is a weighted sumof a 50 Hz sinusoidal signal and a 100 Hz sinusoidal signal, forexample, the frequency filter unit 1105 b may attenuate the 50 Hzsinusoidal signal by 50% (while completely blocking the 100 Hz componentof the drive signal), and the frequency filter unit 1105 c may attenuatethe 100 Hz sinusoidal signal by 25% (while completely blocking the 50 Hzcomponent of the drive signal). In an embodiment, each of the frequencyfilter units may be configured to introduce a phase shift into afrequency component of a signal that falls within a pass-through band ofthe frequency filter unit. The phase shift may introduce a delay bywhich the drive signal reaches a respective electrode connected to thefrequency filter unit.

In an embodiment, the frequency filter units of a haptic enabledinterface device may have pass-through bands with the same bandwidth, orwith different respective bandwidths. In an embodiment, a bandwidth foreach pass-through band may be nonzero (e.g., 20 Hz). In an embodiment, abandwidth for a pass-through band may be small enough such that thepass-through band may be treated as a pass-through frequency (e.g., apass-through frequency of 50 Hz, 100 Hz, or 200 Hz). The pass-throughfrequency may be associated with a digital frequency filter unit thatperforms digital signal processing (e.g., a Fourier transform) toperform filtering.

In the embodiment of FIG. 5A, the respective pass-through frequencybands of frequency filter units 1105 b (one band centered around 50 Hz),1105 c (one band centered around 100 Hz), and 1105 d (one band centeredaround 200 Hz) do not overlap. This embodiment allows the control unit110 to create a first drive signal that reaches only one ESF electrode.For example, the control unit may cause the first drive signal to have afrequency component of only 50 Hz, such that only frequency filter unit1105 b will pass the first drive signal to electrode 103 b, and onlyelectrode 103 b will produce or generate an ESF effect based on thefirst drive signal. However, the control unit may also cause a seconddrive signal in this embodiment to reach multiple electrodes, byincluding multiple frequency components (e.g., 50 Hz and 100 Hz) in thesecond drive signal. In another embodiment, the respective pass-throughfrequency bands of a plurality of frequency filter units may have someoverlap.

FIG. 5B shows an embodiment in which some frequency filter units mayhave respective sets of pass-through frequency bands. More specifically,the embodiment of FIG. 5 includes a frequency filter unit 2105 b thathas a respective set of pass-through frequency bands that includes aband centered around 50 Hz, a band centered around 100 Hz, and a bandcentered around 200 Hz. Frequency filter unit 2105 d has a respectiveset of pass-through frequency bands that includes a band also centeredaround 100 Hz and another band also centered around 200 Hz. Frequencyfilter unit 2105 c has a single respective pass-through frequency bandalso centered around 100 Hz. In the embodiment depicted in FIG. 5B, therespective pass-through frequency band (of filter unit 2105 c) orrespective sets of pass-through frequency bands (of filter units 2105 band 2105 d) have partial overlap in frequency (e.g., at 100 Hz and 200Hz). In another embodiment, a plurality of frequency filter units mayhave respective pass-through frequency bands or respective sets ofpass-through frequency bands that do not overlap in frequency.

In an embodiment, control unit 110 may be configured to use thefrequency filter units 2105 b, 2105 c, and 2105 d to cause only a subsetof one or more electrodes of the set of electrodes 103 b, 103 c, and 103d to output one or more respective ESF effects with a first drivesignal. For instance, the control unit may generate the first drivesignal with only a frequency component of 200 Hz. In that instance, onlyelectrodes 103 b and 103 d will output respective ESF effects with thefirst drive signal. In an embodiment, the control unit may be configuredto cause at least two electrodes of electrodes 103 b, 103 c, and 103 dto output respective ESF effects with the first drive signal, but to doso in different manners. For instance, the first drive signal with the200 Hz frequency component may be attenuated by 70% by frequency filterunit 2105 b, and may be attenuated by 50% by frequency filter unit 2105d. Thus, the two respective electrodes 103 b and 103 d may receive thefirst drive signal with different levels of attenuation, and thus outputrespective ESF effects with the first drive signal in different manners.In another example, the first drive signal may include frequencycomponents of only 100 Hz and 200 Hz. As shown in FIG. 5B, the frequencyfilter unit 2105 c will filter out the 200 Hz component of the firstdrive signal, while the frequency filter units 2105 b and 2105 d willnot. Accordingly, electrodes 103 b and 103 d are driven by the 100 Hzand the 200 Hz frequency components of the first drive signal, whileelectrode 103 c is driven by only the 100 Hz frequency component of thefirst drive signal. Thus, the three electrodes 103 b, 103 c and 103 dmay output respective ESF effects with the first drive signal indifferent manners, because the three electrodes are driven by differentcombinations of frequency components and provide different levels ofattenuation.

FIG. 6A depicts an embodiment in which gating elements thereof are aplurality of delay elements 3105 b-3105 d, respectively. Each delayelement of delay elements 3105 b-3105 d may be configured to control atiming by which a respective electrode of electrodes 103 b-103 d willoutput a respective ESF effect. A delay element may control this timingby introducing a different respective period of delay of a drive signalfrom an output of the signal generating circuit 104 to the respectiveelectrode. In an embodiment, each of the delay elements may be an analogdelay element, such as an inductive and/or capacitive filter (e.g., a LCfilter). In another embodiment, each of the delay elements may be adigital delay element, such as a buffer. In FIG. 6A, delay element 3105b may be configured to introduce a delay “d1” (e.g., 500 msec), delayelement 3105 c may be configured to introduce a delay “d2” (e.g., 700msec), and delay element 3105 d may be configured to introduce a delay“d3” (e.g., 900 msec) to a drive signal. In the embodiment of FIG. 6A, adelay in traversing a physical distance from the signal generatingcircuit 104 to a particular electrode may be considered negligible. Thedelay elements 3105 b, 3105 c, and 3105 d may be configured to cause theelectrodes 103 b, 103 c, and 103 d to output respective ESF effects in asequence, at t₀+d1, t₀+d2, and at t₀+d3, respectively. In an embodiment,d1, d2, and d3 increase in value in a linear fashion. For instance,d2=2×d1, while d3=3×d1. The delay elements 3105 b, 3105 c, and 3105 dmay then cause the electrodes 103 b, 103 c, and 103 d to outputrespective ESF effects in a sequence, at t₀+d1, t₀+2d1, and at t₀+3d1.The sequential output of ESF effects across electrodes 103 b, 103 c, and103 d may provide the sensation of flow described above.

While FIG. 6A illustrates an embodiment in which a plurality of delayelements 3105 b, 3105 c, and 3105 d may each be connected to an outputof the signal generating circuit 104 in a parallel configuration, FIG.6B illustrates an embodiment in which a plurality of delay elements 4105b, 4105 c, and 4105 d are connected to each other in a series fashion toform a chain of delay elements so that a drive signal propagates throughthe chain of delay elements. More specifically, FIG. 6B depicts aninterface device that includes delay elements 4105 b, 4105 c, and 4105 dand respective ESF electrodes 103 b, 103 c, and 103 d that operablycorrespond to the delay elements. Delay elements 4105 b, 4105 c, and4105 d may be configured to introduce delays of d1, d2, and d3,respectively, from an input of the delay element to an output of thedelay element. The delay elements may be spatially arranged as a line orother array of delay elements, and the electrodes may be spatiallyarranged as a line or other array of electrodes. Each of the electrodes103 b, 103 c, 103 d may be electrically connected to an output of arespective delay element. FIG. 6B further includes a signal generatingcircuit 104 that is configured to generate a drive signal.

As shown in FIG. 6B, the delay elements 4105 b, 4105 c, and 4105 d andtheir respective electrodes 103 b, 103 c, 103 d may form or otherwise begrouped into respective pairs that each includes a respective delayelement and a respective electrode. For instance, delay element 4105 band electrode 103 b may form a pair 1, delay element 4105 c andelectrode 103 c may form a pair 2, and delay element 4105 d andelectrode 103 d may form a pair 3. The pairs of delay elements andelectrodes (e.g., pair 1, pair 2, and pair 3) may be electricallyconnected in series. In an embodiment, the pair 1 may be a first pair inthe series, the pair 2 may be a second pair in the series, and the pair3 may be a third pair in the series. By being connected in series, aninput of a delay element of a first pair in the series (i.e., an inputof delay element 4105 b) may be connected to an output of the signalgenerating circuit 104, while an input of a delay element of all otherpairs in the series is electrically connected to an electrode of aprevious pair in the series. Thus, an input of a delay element of thesecond pair in the series (input of delay element 4105 c) may beconnected to an electrode of the first pair in the series (electrode 103b), while an input of a delay element of the third pair in the series(input of delay element 4105 d) may be connected to an electrode of thesecond pair in the series (electrode 103 c). With this arrangement, adrive signal may propagate through the series of delay elements andelectrodes to sequentially output ESF effects along the electrodes. Eachelectrode may experience a cumulative delay of its delay element and ofdelay elements in previous pair of the series. Thus, electrode 103 b mayexperience a delay of d1, electrode 103 c may experience a delay ofd2+d1, and electrode 103 d may experience a delay of d3+d2+d1. In anembodiment, d1=d2=d3. In an embodiment, at least some or all of d1, d2,and d3 have different values.

In an embodiment, each of the delay elements in FIGS. 6A and 6B isconfigured to introduce a respective period of delay, a time delay orperiod of delay, to a drive signal from an input of the delay element toan output of the delay element. The delay elements may be configured tointroduce the same period of delay, or to introduce different respectiveperiods of delay.

In an embodiment, each of the delay elements in FIGS. 6A and 6B may havea fixed delay, or may have a reconfigurable delay. For instance, eachdelay element may be a capacitor with a fixed capacitance, or areconfigurable capacitance.

FIG. 7 depicts an embodiment in which a plurality of gating elements arerelay switches 5105 b-5105 d. The relay switches may be controlled by,e.g., the control unit 110 in FIG. 4A. In an embodiment, the controlunit 110 may be configured to close only one relay switch of all therelay switches that are being used as gating elements, and to leave allother relay switches open. In an embodiment, the control unit 110 may beconfigured to close multiple relay switches at the same time, and toleave open other relay switches being used as gating elements. In anembodiment, each of the relay switches 5105 b-5105 c may be a highvoltage relay switch configured to withstand a voltage (e.g., 1 kV) usedto generate static ESF effects. When a particular switch is in an openstate as shown in FIG. 7, an electrode connected to the switch may be inan electrically floating state.

As discussed above, generating an ESF effect may involve a signalelectrode and a ground electrode. An insulated electrode may be usableas a signal electrode at one point in time by being electricallyconnected to an output of a signal generating circuit, and as a groundelectrode at another point in time by being electrically connected to aground potential. FIG. 8A schematically represents an embodiment inwhich each electrode of electrodes 103 a-103 g may be an insulatedelectrode switchable between being a signal electrode and being a groundelectrode. More specifically, FIG. 8A shows a signal generating circuit104, a control unit 110, a plurality of electrodes 103 a-103 g (e.g.,insulated electrodes), and gating elements 105 a-105 h, similar to FIG.4A. However, FIG. 8A further shows a plurality of gating elements 115a-115 h that are each electrically connected to a ground potential. Inone example, while gating elements 105 a-105 h may control which subsetof electrodes will receive a drive signal from the signal generatingcircuit 104, the gating elements 115 a-115 h may be configured to groundthose electrodes that are not receiving a drive signal or not intendedto receive the drive signal.

In an embodiment depicted in FIG. 8B, an electrode may be groundedrather than be left in an electrically floating state when itsrespective gating element is in an open state. In the embodiment of FIG.8B, the gating elements 5115 a-5115 h are relay switches, and moreparticularly, include a first plurality of relay switches 5105 b, 5105c, 5105 d, and a second plurality of relay switches 5115 b, 5115 c, 5115d. The gating elements may form pairs, such as a first pair of switches5105 b, 5115 b, a second pair of switches 5105 c, 5115 c, and a thirdpair of switches 5105 d, 5115 d. In an embodiment, each of the relayswitches may be controlled by the control unit 110. Each of the relayswitches 5105 b, 5105 c, 5105 d may be operably controlled toselectively connect a corresponding electrode to an output of the signalgenerating circuit 104, while each of the relay switches 5115 b, 5115 c,and 5115 d may be operably controlled to selectively connect thecorresponding electrode to ground. The pairs of relay switches may beconfigured or controlled so that exactly one relay switch in each pairwill be closed during operation of the haptic interface device. Thisway, if an electrode is not electrically connected to the output of asignal generating circuit, the electrode is grounded rather than left inan electrically floating state.

FIG. 9 provides an embodiment in which a plurality of shielding elements113 a-113 h may control which electrodes 103 a-103 h output an ESFeffect with a first drive signal. The shielding elements 113 a-113 h maybe combined with the gating elements 105 a-105 h in FIG. 4A, but alsoallows such gating elements to be omitted such that each of theelectrodes 103 a-103 h receives a drive signal(s) from the signalgenerating circuit 104. In an embodiment, each of the electrodes 103a-103 h may be an insulated electrode that is disposed behind an outersurface of a haptic enabled interface device. The plurality of shieldingelements 113 a-113 h may be disposed in front of (on top of or above)respective electrodes 103 a-103 h, such that the shielding elements 113a-113 h are located between the electrodes 103 a-103 h and an outersurface of the interface device. For example, the shielding element 113a-113 h may be conductive pads (e.g., metal pads) buried slightly behind(below) an outer surface of the interface device, but at a shallowerdepth compared to the electrodes 103 a-103 h. In an embodiment, eachshielding element of the shielding elements 113 a-113 h may have thesame dimensions as a respective electrode of the electrodes 103 a-103 h,and may be disposed directly in front of (e.g., directly above) therespective electrode.

In an embodiment, each shielding element of the shielding elements 113a-113 h is switchably connectable to ground, via a respective gatingelement (e.g., switch) of the gating elements 115 a-115 h, which may becontrolled by the control unit 110. In this embodiment, each of theelectrodes 103 a-103 h may be electrically connected to an output of asignal generating circuit 104. Each of the electrodes 103 a-103 h maygenerate an electric field based on the drive signal. A shieldingelement (e.g., 113 b) of the shielding elements 113 a-113 h may suppressthe electric field emanating from a respective electrode (e.g., 103 b)by being switchably connected to ground, such as via a respective gatingelement (e.g., 115 b) of the gating elements 115 a-115 h. When theshielding element is electrically connected to ground, it may block theelectric field of a respective electrode from reaching an outer surfaceof the interface device. Thus, this shielding element may prevent thecorresponding electrode (e.g., 103 b) from generating an ESF effect withthe drive signal. Another electrode (e.g., 103 c) may be allowed togenerate an ESF effect with the drive signal by having its respectiveshielding element (e.g., 113 c) electrically disconnected from ground.Shielding elements are discussed in more detail in U.S. application Ser.No. 15/239,464 (Atty Dkt. No. IMM627), filed on Aug. 17, 2016, thecontent of which is incorporated by reference herein in its entirety.

FIG. 10 depicts an embodiment in which the gating elements thatswitchably connect shielding elements to ground are relay switches 5115b-5115 d, respectively. Any of the relay switches may be closed toelectrically connect a respective shielding element to ground, or may beopened to electrically disconnect the respective shielding element fromground.

FIGS. 11A and 11B depict embodiments in which the plurality ofelectrodes shown above (e.g., electrodes 103 a-103 h or 203 a-203 e) areused to provide spatial feedback and/or temporal feedback (which may bereferred to generally as spatio-temporal feedback) with ESF effects. Inan embodiment, spatial feedback may indicate a spatial orientation of ahaptic interface device relative to a location of interest. The locationof interest may be a particular final destination (e.g., a friend'shouse) or intermediate destination (e.g., a highway on-ramp), a locationof an event (e.g., a concert), or any other location of interest, suchas a location of an object (e.g., a car). The spatial feedback mayindicate, for instance, a direction of a location of interest relativeto a haptic enabled interface device (or relative to a user wearing thedevice). For example, FIG. 11A shows a haptic enabled interface device100′ which may include at least electrodes 103 b and 103 g from FIG. 1Aand electrode 203 a from FIG. 1B. If the location of interest is to theleft of (or, e.g., to the west of) the device 100′, electrode 103 b mayoutput an ESF effect with a drive signal. If the location of interest isto the front of (or, e.g., to the north of) the device 100′, electrode203 a may output an ESF effect with the drive signal. If the location ofinterest is to the right (or, e.g., to the east of) the device 100′,electrode 103 g may output an ESF effect with the drive signal. In anembodiment, a direction that constitutes front (or left or right) may bebased on a direction that a user is facing. The direction that the useris facing may be determined when the device 100′ is worn or being held.This determination may use, e.g., any integrated motion sensor (e.g.,accelerometer or gyroscope), any integrated compass, or any integratedglobal positioning system (GPS). In an embodiment, the selection ofwhich electrode(s) will represent a particular direction or orientationmay be predetermined and fixed. In an embodiment, such a selection maybe re-configurable, and may be based on how the device (e.g., 100′) isworn or held.

FIG. 11B depicts an embodiment of producing spatial feedback that may besensed as a flow. More specifically, FIG. 11B depicts the wearableinterface device 100 of FIG. 1A that includes at least electrodes 103 b,103 c, 103 d, and 103 e spatially arranged in a line or other array. Theelectrodes 103 b, 103 c, 103 d, and 103 e may sequentially outputrespective ESF effects in a clockwise order around a user's wrist, or ina counterclockwise order around the user's wrist to provide a feeling offlow to the user in corresponding clockwise or counterclockwisedirection. The clockwise direction may indicate, e.g., a rightwarddirection (e.g., the user needs to move to the right), while thecounterclockwise direction may indicate, e.g., a leftward direction(e.g., the user needs to move to the left).

In an embodiment, the sense of flow may be created with one drivesignal, or with multiple drive signals. For example, the sense of flowmay be created with one drive signal and the multiple delay elementsshown in FIG. 6A or 6B. The delay elements may allow a drive signal topropagate to electrode 103 b at a first time (e.g., t₀+d) to generate afirst ESF effect, allow the drive signal to propagate to electrode 103 cat a second time (e.g., t₀+2d) to generate a second ESF effect, allowthe drive signal to propagate to electrode 103 d at a third time (e.g.,t₀+3d) to generate a third ESF effect, and to propagate to electrode 103e at a fourth time (e.g., t₀+4d) to generate a fourth haptic effect.

In another example, the sense of flow may be created with multiple drivesignals and the frequency filter units or relay switches shown in FIGS.5A, 5B, and FIG. 7. For instance, a first drive signal may be generatedat a first time (e.g., t₀+d) and be applied to only electrode 103 b byblocking the first drive signal from all other electrodes, using thefrequency filter units or relay switches. Then, a second drive signalmay be generated at a second time (e.g., t₀+2d) and be applied to onlyelectrode 103 c by blocking the second drive signal from all otherelectrodes. This process may be repeated for at least a third drivesignal (applied to only electrode 103 d) and a fourth drive signal(applied to only electrode 103 e).

In an embodiment, creating or producing a sense of flow may be used toconvey a temporal relationship between a current time and an event ofinterest (e.g., a temporal relationship between a current time and ameeting), as discussed above. In an embodiment, creating or producing asense of flow may be used to convey information such as the status of anoperation.

In an embodiment, the gating elements discussed above may be used tocreate particular ESF effects by implementing a sequence of at least afirst electrode, a second electrode, and a third electrode, in which thesecond electrode is a middle electrode, and the first and thirdelectrodes are immediately next to the middle electrode and on oppositesides of the middle electrode. For instance, in order to generate aparticular ESF effect, the gating elements may allow a drive signal toreach the first electrode and the second electrode, but not the thirdelectrode.

FIGS. 12 and 13 illustrate other embodiments of shapes and arrangementsof electrodes (e.g., static ESF electrodes) used to generate ESF effectsfor a haptic interface device. FIG. 12 shows a haptic enabled interfacedevice 500 that is an armband. The device 500 may include an electrode503 a shaped as an ellipse that is disposed at a surface of the device500, and an electrode 503 b shaped as a line or bar that is disposed atthe surface of the device 500. As shown in FIG. 12, the electrode 503 amay surround the electrode 503 b. FIG. 13 shows a haptic interfacedevice 600 that has a plurality of electrodes 603 a, 603 b, 603 c, 603 dthat are arranged as concentric circles and disposed at a surface of thehaptic enabled interface device 600. The arrangement of the electrodesmay allow them to sequentially create respective ESF effects that createan impression of inward or outward flow.

As discussed above, the array of static ESF electrodes may have avariety of shapes and arrangements, such as long strips (e.g., disposedover the length of a bracelet), small dots (e.g., all over the surfaceof a phone), or a 2D array of large squares (e.g., on the back of atablet computer). In an embodiment, long strips and larger pads mayprovide better static ESF effects than smaller electrodes, because theyare less likely to be completely covered by a user's skin.

Embodiments herein may be used for a mobile phone, gaming, automotive,augmented reality (AR), virtual reality (VR), or wearables application.For example, the handheld interface device may be a controller for a VRor AR application. In an embodiment, the electrodes may be used toexpand the expressivity of static ESF feedback by producing a variety ofspatial and/or temporal effects.

Embodiments herein may be used for dynamic ESF effects or static ESFeffects. For static ESF effects, the drive signal applied to theselected subset of the plurality of electrodes may have an amplitude ofat least 1 kV.

While various embodiments have been described above, it should beunderstood that they have been presented only as illustrations andexamples of the present invention, and not by way of limitation. It willbe apparent to persons skilled in the relevant art that various changesin form and detail can be made therein without departing from the spiritand scope of the invention. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the appendedclaims and their equivalents. It will also be understood that eachfeature of each embodiment discussed herein, and of each reference citedherein, can be used in combination with the features of any otherembodiment. All patents and publications discussed herein areincorporated by reference herein in their entirety.

1-18. (canceled)
 19. An interface device configured to provide anelectrostatic friction (ESF) effect, the interface device comprising: asignal generating circuit configured to generate a first drive signal atan output of the signal generating circuit; a first electrode disposedat a surface of the interface device and permanently electricallyconnected to a source of ground potential; a second set of electrodesdisposed at the surface of the interface device, wherein the firstelectrode is not part of the second set of electrodes; a plurality ofgating elements, wherein each gating element of the plurality of gatingelements comprises at least one switch and is configured to switchbetween (a) electronically connecting a respective electrode of thesecond set of electrodes to the output of the signal generating circuitand (b) electrically connecting the respective electrode to the sourceof ground potential or leaving the respective electrode in anelectrically floating state; a control circuit configured to select oneor more electrodes of the second set of electrodes to output the ESFeffect with the first drive signal, to control the plurality of gatingelements to electrically connect the one or more electrodes that havebeen selected to the output of the signal generating circuit, and tocontrol the plurality of gating elements to either: electrically connectall unselected electrodes of the second set of electrodes to the sourceof ground potential, or leave all unselected electrodes of the secondset of electrodes in the electrically floating state.
 20. The interfacedevice of claim 19, wherein the signal generating circuit comprises asignal processor and an amplifier, wherein the signal processor isconfigured to generate an initial drive signal, and the amplifier isconfigured to amplify the initial drive signal to generate the firstdrive signal, and wherein each gating element of the plurality of gatingelements is electrically connected to an output of the amplifier. 21.The interface device of claim 20, wherein the amplifier is configured togenerate the first drive signal with an amplitude of at least 1 kV. 22.The interface device of claim 21, wherein the signal generating circuitis configured to generate the first drive signal as a pulse with theamplitude of at least 1 kV.
 23. The interface device of claim 21,wherein the amplifier is the only amplifier of the signal generatingcircuit for amplifying any signal from the signal processor.
 24. Theinterface device of claim 23, wherein each electrode of the second setof electrodes is an insulated electrode.
 25. The interface device ofclaim 24, wherein the first electrode is an exposed electrode.
 26. Theinterface device of claim 20, wherein the at least one switch of arespective gating element of the plurality of gating elements is a relayswitch or a transistor.
 27. The interface device of claim 19, whereinthe control circuit is configured to select only one electrode of thesecond set of electrodes to generate the ESF effect with the first drivesignal, to control the plurality of gating elements to electricallyconnect only the one electrode that is selected to the output of thesignal generating circuit, and to control the plurality of gatingelements to electrically connect all unselected electrodes of the secondset of electrodes to the source of ground potential.
 28. The interfacedevice of claim 19, wherein the interface device is a wearable devicehaving a band, wherein the surface of the interface device includes asurface of the band, and wherein the plurality of electrodes aredisposed at the surface of the band.
 29. The interface device of claim28, wherein each electrode of the second set of electrodes is shaped asa strip.
 30. The interface device of claim 19, wherein the second set ofelectrodes are arranged as a two-dimensional array.
 31. The interfacedevice of claim 19, wherein the control circuit is configured todetermine a spatial relationship between a location of an object orevent and a location of the interface device, wherein the controlcircuit is configured to select the one or more electrodes of the secondset of electrodes based on the spatial relationship between the locationof the object or event and the location of the interface device.
 32. Theinterface device of claim 19, wherein the control circuit is configuredto determine a temporal relationship between a time of an event and acurrent time, wherein the control circuit is configured to select theone or more electrodes of the second set of electrodes based on thetemporal relationship between the time of the event and the currenttime.
 33. The interface device of claim 19, wherein each gating elementof the plurality of gating elements comprises a first switch and asecond switch, wherein the first switch is configured to switch betweenelectrically connecting a respective electrode of the second set ofelectrodes to the output of the signal generating circuit and leavingthe respective electrode in the electrically floating state, and whereinthe second switch is configured to switch between electricallyconnecting the respective electrode to the source of ground potentialand leaving the respective electrode in the electrically floating state.34. The interface device of claim 19, wherein the control circuit isconfigured to select the one or more electrodes from among a subset ofthe second set of electrodes, the subset of electrodes receiving usercontact, such that some electrodes of the second set of electrodesreceiving user contact are not selected to generate a respective ESFeffect with the first drive signal.
 35. The interface device of claim19, wherein the interface device is a mobile device, and the second setof electrodes are disposed on a back surface of the mobile device. 36.The interface device of claim 35, wherein each electrode of the secondset of electrodes is shaped as a circle or as a square.